Monday has arrived with one of the biggest sporting events in the U.S.- the 2013 Boston Marathon.

The event has taken place each year on Patriots' Day, the third Monday in April, since 1897. The Boston Marathon is the world's oldest annual marathon, and is among the world's most famous road racing events.

This year, the weather in Boston is expected to provide ideal conditions for runners, with temperatures in the mid-50s and calm winds.

Last year, however, hot temperatures proved hugely problematic for runners, who were offered an automatic entry in the 2013 race if they sat it out. Nearly 2,300 runners opted to do just that, and today, approximately 27,000 contenders have hit the pavement.

"We got a bye," race director Dave McGillivray told the Associated Press. "And that's good, because we need this year to regroup."

Among those racing today are an inspirational group of 40 blind runners. Their participation will raise awareness and money for programs such as the Massachusetts Association for the Blind and Visually Impaired, according to MSN.